Photographic emulsions containing fluorine substituted ethylene polymers as delustering agents



United States Patent" PHOTOGRAPHIC EMULSIONS CONTAINING FLU- ORINE SUBSTITUTE ETHYLENE PDLYMERS AS DELUSTERING AGENTS Russell H. Gray, Red Bank, N. J., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Application October 20, 1951, Serial No. 252,410

18 Claims. (Cl. 95-7) This invention relates to photography and more particularly to delustered sions and emulsion layers and to photographic elements bearing the same. The invention also relates to a process of preparing such emulsions.

An object of this invention is to provide improved photographic silver halide emulsions. A further object is to provide photographic silver halide emulsion layers which have a delustered surface. A still further object is to provide a process of making such emulsions and layers which do not have a deleterious effect on the photographic properties of the emulsion. Yet another object is to providephotographic elements with such layers which have enhanced. resistance to physical abrasion. Still other objects will be apparent from the following description of the invention.

The above objects are attained and improved photographic silver halide emulsions, emulsion layers and elements, e. g., films, plates, papers, etc., provided by incorporating with the emulsion an aqueous dispersion of a fluorine-substituted ethylene polymer obtained, from fluorine-substituted ethylene monomers. which contain 3 to 4.1luorine atoms and a hydrogen atom or chlorine atom or a copolymer of such fluorine-substituted mono mers with a monoolefine of 2 to 4. carbon, atoms or a monoor di-fluorine-substituted olefine of 2 to 4 carbon atoms wherein the latter component constitutes 2 to 35% by weight of the resulting copolymer.

The polymers may be made from trifluoroethylene. chlorotrifluoroethylene or tetrafiuoroethylene or mixtures thereof, or from mixtures of the latter, one, two. or all three of such fluoroethylenes with. ethylene, propylene, butene-l, butene-Z, vinyl fluoride or 1,1-difiuoroethylene. The preparation of the polymers including the copolymersis well known in the art. and. does not constitute a part of this invention. Suitable methods for their preparation are described in the following United Statespatents:

2, s92, ass.

April 15, 194%.

July 10, 1951.

silver halide photographic emul- Photovolt Corporation, 95. Madison Ave.,

such polymers which have a negativecharge and a: small amount of a suitable. wetting or dispersing agent toincrease the stability of the dispersion. The solids content may range from 10% and below to 60% and. above. The pH may range from 21.0. It is generally best to use a non-ionic wetting agent or one having the same charge as the polymer, viz., ananionic wetting agent.

The particle size of the polymers in the aqueous dispersion may vary over a. fairly wide range, e. g., from 0.05 to 25.0 microns but is generally 0.05 to 0.5 micron. The fact that the small particle sizes deluster the silver halide emulsion layers so efiiciently is quite surprising since it has been generally accepted by the art that the particle size should be from 1. to lOmic-rons.

While aqueous dispersions of the triand tetra-fluorine substituted ethylene polymers are generally admixed. with the aqueous colloid-silver halide emulsions to form photographic elements with improved surfaces the invention is not limited to this aspect. To the contrary, the aqueous dispersions may be admixed with an aqueous colloid coating solution, e. g., gelatin, polyvinyl alcohol, etc., and coated onto the colloid silver emulsion layer to form a thin, protective layer.

The invention is further illustrated but is not intended to be limited by the following examples.

Example I A slow speed contact printing paper gelatin silver chlorobromide emulsion (AgCl='.2' mole percent, AgBr=4.8 mole percent) was prepared and was brought to optimum speed level preparatory to coating and additions of a sensitizing dye, glycerine, benzotriazole and chrome alum were made. To equal portions of this emulsion were added various quantities of a. 50% solids content of an aqueous dispersion of a tetrafluoroethylene polymer wherein 85% of the particles were approximately 0.25 micron in diameter and smaller and containing a small amount of an octyl phenylpolyglycol ether as a dispersing agent. These portions were then coated onto a baryta coated' paper" stock and dried. Samples of these coatings werethenexposed in contact with a standard negative in acontact printer so thatprints matched for photographic quality were obtained upon development in a solution of the following com- Waterto make 1,0

for 1.5 minutes at 68 F. Theres ulting prints were fixed, washed and driedvwith the final results asshowm Polytetrafluoroethylene Dispersion Relative 75 Gloss MIL/Liter Emulsion. Speed, (or sheen) None l 68 5.0 100 50 20.0 9s 21- The gloss or sheen was measured for 75 gloss on a Photovolt. Model 660? Gloss. Meter manufacturedby New York, N. Y. This type of gloss meter is-described in Chem. Ind. 1943, 1. 74s.

Example H A gelatin; silver bromochloride emulsion of normal speed for printing paper enlarging (fAgBr=7{6.2 mole percent, AgCl=2318 mole percent) was prepared and to Separate portions there were added varying amounts of an aqueous dispersion of a tetrafluoroethylene polymer similar in particle size of Example I as shown in the following table. The resulting emulsions were coated respectively onto a baryta coated paper base to form a thin layer and dried. Samples of these coatings were then exposed to a standard negative in a diffuse-light enlarger so that prints matched for photographic quality were obtainedupon development as specified in-Group l. The 75 gloss was measured on the finished and dry prints by means of the instrument specified in Example 1.

m1. polytetra Grams polytetrafluoroethylone g g Relative 75 per 1.5 mole silver halide suspensoid Speed Gloss per liter Example III Gelatino silver halide emulsions were prepared as described in Example I except that the pH of the dispersion had been adjusted to 9-10 with ammonium hydroxide with the following results:

Grams ol etrafluoroethylene per 1.5 mole silver Relative 75 p yt halide Speed Gloss Delustering was obtained also by substituting for the dispersing agent of that example a similar amount of sodium dodecyl sulfate.

Example IV The process described in Example I was repeated by substituting for the polytetrafluoroethylene an aqueous polychlorotrifluoroethylene dispersion having a particle size range of 1-6 microns with the following results:

Polyehlorotrifluoroethylene grams per 1.5 moles Relative 75 silver halide Speed Gloss Example V The process described in Example I was repeated by substituting for the polymer of that example a copolymeric (equimolar) ethylene/tetrafluoroethylene aqueous dispersion with the results given in the following table:

i Realtive 75 Grams eopolymei per 1.5 moles silver halide Speed G1 055 None 100 71 220.0 61 58 Example VI by weight. These solutions were then respectively coated of the gloss on the instrument described in Example I, V

the following was observed:

Polytetrafluoroethylene grams per liter gelatin solution 75 Gloss Similar results are obtained by coating the gelatin-polymer dispersion on a gelatino silver halide emulsion layer disposed on the subbed film base.

Example VII Grams polytetrafluoroethylene per liter FHA solution 75 Gloss Similar results are obtained by coating the colloid-polymer dispersion onto a polyvinyl acetal color former silver halide emulsion of the type described in Jennings et al. U. 8. Patent 2,397,864 dispersed on a film support as described in that patent.

'Among the useful dispersing agents which can be used in the aqueous polymer dispersions are octyl phenyl polyglycol ether, sodium decyl sulfate, sodium tetradecyl sulfate, sodium hexadecyl sulfate, sodium octadecyl sulfate, polyoxyethylene sorbitan monolaurate and mixtures of one or more of such compounds. In general, they are used in an amount of 0.5 to 10% by weight of the aqueous dispersion.

The invention is not limited to the particular emulsions of the foregoing examples as other silver halide emulsions can be similarly treated including simple and mixed emulsions of silver chloride, silver bromoiodide, silver chlorobromoiodide, etc. Similarly, it is not limited to the particular colloid binding agents for the silver halide grains and other hydrophilic or water-soluble colloids or mixtures can be substituted. Suitable additional colloids include agar-agar, polyglycuronic acids, zein, collodion, water-soluble cellulose derivatives, such as substantially hydrolyzed cellulose acetate, cellulose esters of hydroxy monocarboxylic acids, e. g., lactic or glycolic acids, alkali metal salts of cellulose esters of dicarboxylic acids, such as phthalic acid; polyvinyl alcohol, partially hydrolyzed polyvinyl acetate and interpolymers thereof with unsaturated materials, such as styrene, maleic acid, etc, watersoluble polyvinyl acetals and other hydrophilic synthetic or natural resins and polymeric compounds. Suitable hydrophilic colloids of the above types are described in United States Patents 2,110,491, 2,276,322, 2,276,323, 2,286,215, and 2,211,323.

It is obvious that the photographic elements may have supports difierent from those of the foregoing examples. Suitable supports include cellulose derivatives e. g., cellulose nitrate, cellulose triacetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate; superpolymers, e. g., polyvinyl chloride and copolymers thereof with a monoethylenically unsaturated monomer; polystyrene, polyacrylonitrile, polyvinyl fluoride, nylon, polyesters of glycols and dicarboxylic acids, e. g., polyethylene terephthalates; glass, transparentized paper, etc.

During the digestion stage or'prior thereto,'various types of sensitizing agents, e. g., sulfur sensitizers, such as allylthioureas, thiocyanates, or allylthiocyanates, can be used. In addition, various types of optical sensitizing dyes which modify the spectral characteristics of the relayers show definite protuberances in arenas sulting emulsions can be added. Suitable sensitizing dyes are described in United States Patents 2,010,388, 2,079,376, 2,202,990, 2,202,991, 2,202,992, 2,278,461, 2,265,908, etc.

In general, the above polymers may be added to the hydrophilic and water-permeable colloid silver halide emulsions over a wide range of proportions. On a solid basis they may vary, for example, from0.5 to 100.0 grams per liter of emulsion and preferably from 50-500 grams per 1.5 mols of silver halide.

Even though the triand tetra-fiuoroethylene polymer and copolymer aqueous dispersions have an extremely fine particle size,

the surfaces of the colloid layers have excellent delustered characteristics. Moreover, the dried the range of 1 to microns.

The surfaces of the photographic elements are superior to those obtained with starch and silica particles which are used commercially in a number of respects as outlined below. A decided commercial advantage over the above materials is that the polymer particles do not separate or settle out in the coating solution. Greater uniformity is attained. They do not cause sedimentation in the emulsion.

The use of the triand tetra-fluorine-substituted ethylene polymers has the advantage that they provide colloid layers which have good delustered surface characteristics and they can be obtained in a simple manner. The polymers have special advantages in photographic silver halide emulsions and emulsion layers in that they are inert, have excellent heat resistance and do not break down upon hot drying to produce irregular areas of high sheen. They, therefore, are far superior to the com ventional starch particles. The emulsion layers have excellent properties for oil coloring and do not increase dye stain.

An important advantage of the invention is that the surface of the photographic elements delustered with the above polymers have a much smoother, more velvety texture to the touch. A still further advantage is that smooth surface papers coated with emulsions containing these resinous delustering particles are matted when air dried yet if the papers are ferro-typed or pressed in intimate contact with a smooth surface during drying, the surface of the dried paper exhibits a sheen as high as one dried similarly yet containing no delusterant.

As many widely different embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined by the claims.

What is claimed is:

1. A process of delustering water-permeable, organic, protective colloid layers which comprises admixing an aqueous solution of water-permeable, organic, protective colloid with an aqueous dispersion of finely divided particles of an ethylenic addition polymer at least 65% by weight of the polymer units being fluorine-substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes within the range of 0.05 to 25.0 microns, and coating the resulting dispersion onto a sheet support.

2. A process of delustering gelatin layers which comprises admixing an aqueous solution of gelatin with an aqueous dispersion of finely divided particles of an ethylenic addition polymer at least 65% by weight of the polymer units being fluorine-substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes within the range of 0.05 to 25.0 microns, and coating the resulting dispersion onto a sheet support.

3. A process of delustering water-permeable, organic, protective colloid layers which comprises admixing an aqueous solution of water-permeable, organic, protective colloid with an aqueous dispersion of finely divided particles of polytetrafluoroethylene, said particles having sizes within the range of 0.05 to 25.0 microns, and coating the resulting dispersion onto a sheet support.

4. A process of delustering water-permeable, organic, protective colloid layers which comprises admixing an aqueous solution of water-permeable, organic, protective colloid with an aqueous dispersion of finely divided particles of a tetrafluoroethylene/ethylene copolymer containing at least 65 by weight of the former, said particles having sizes within the range of 0.05 to 25.0 microns, and coating the resulting dispersion onto a sheet support.

5. A process of delustering photographic water-permeable, organic, protective colloid silver halide emulsion layers which comprises admixing an aqueous dispersion of light-sensitive silver halides in a water-permeable, organic protective colloid with an aqueous dispersion of finely divided particles of an ethylenic addition polymer at least 65 by Weight of the polymer units being fluo fine-substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes within the range of 0.05 to 25.0 microns, and coating the resulting dispersion onto a sheet support.

6. A process of delustering photographic gelatino silver halide emulsion layers which comprises admixing an aqueous dispersion of light-sensitive silver halides in gelatin with an aqueous dispersion of finely divided particles of an ethylenic addition polymer at least 65 by weight of the polymer units being fluorine-substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes Within the range of 0.05 to 25.0 microns, and coating the resulting dispersion onto a sheet support.

7. A process of delustering photographic gelatino silver halide emulsion layers which comprises admixing an aqueous dispersion of light-sensitive silver halides in gelatin with an aqueous dispersion of finely divided particles of polytetrafiuoroethylene, said particles having sizes within the range of 0.05 to 25.0 microns, and coating the resulting dispersion onto a sheet support.

8. A light-sensitive, water-permeable organic, protective colloid silver halide emulsion which has uniformly dispersed therethrough as a delustering agent, finely clivided particles of an ethylenic addition polymer at least 65% by weight of the polymer units being fluorinesubstituted ethylene units containing 3 to 4 fiuorine atoms, said particles having sizes within the range of 0.05 to 25 .0 microns.

9. A light-sensitive gelatino silver halide emulsion which has uniformly dispersed therethrough as a delustering agent, finely divided particles of an ethylenic addition polymer at least 65% by Weight of the polymer units being fluorine-substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes within the range of 0.05 to 25.0 microns.

10. A light-sensitive, Water-permeable, organic, protective colloid-silver halide emulsion which has uniformly dispersed therethrough as a delustering agent, finely divided particles of polytetrafluoroethylene, said particles having sizes within the range of 0.05 to 25.0 microns.

11. A photographic element comprising a support bearing a light-sensitive, water-permeable, organic, protective colloid-silver halide emulsion layer, the outer water-permeable stratum of said element in contact with the silver halide grains having uniformly dispersed therethrough as a delustering agent, finely divided particles of an ethylenic addition polymer at least 65% by weight,

stituted ethylene units containing 3 to 4 fluorine atoms,

said particles having sizes within the range of 0.05 to 25.0 microns.

13. A photographic element comprising a baryta coated paper support bearing a light-sensitive, gelatino-silver halide emulsion layer, the outer gelatin stratum of said element in contact with the silver halide grains having uniformly dispersed therethrough as a delustering' agent, finely divided particles of an ethylenic addition polymer at least 65% by weight of the polymer unit being fluorine-substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes within the range of 0.05 to 25.0 microns.

14. A photographic element comprising a sheet support bearing a light-sensitive, water-permeable, organic, protective colloid-silver halide emulsion layer which has uniformly dispersed therethrough finely divided particles of an ethylenic additon polymer at least 65% by weight of the polymer unit being fluorine-substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes within the range from 0.05 to 25.0 microns and being present in an amount of 50 to 500 grams per 1.5 mols of silver halide.

15. A photographic element comprising a baryta coated paper support bearing a light-sensitive, water-permeable,

organic, protective colloid-silver halide emulsion layer which has uniformly dispersed therethrough finely divided particles of an ethylenic addition polymer atleast 65% by weight of the polymer unit being fluorine-substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes within the range from 0.05

to 25.0 microns and being present in an amount of 50 to 500 grams per 1.5 mols of silver halide.

16. A photographic element comprising a sheet sup port bearing a light-sensitive, gelatino silver halide emulsion layer which has uniformly dispersed therethrough finely divided particles of an ethylenic addition polymer at least 65% by weight of the polymer unit being fluorine substituted ethylene units containing 3 to 4 fluorine atoms, said particles having sizes within the range from 0.05 to 25 .0 micronsand being present in an amount of to 500 grams per 1.5 mols of silver halide.

17. A photographic element comprising a sheet support bearing alight-sensitive, water-permeable,v organic, protective colloid-silver halide emulsion which has uniformly dispersed therethrough finely divided particles of V a polytetrafluoroethylene, said particles having sizes within the range from 0.05 to 25.0 microns and being present in an amount of 50 to 500 grams per 1.5 mols of silver halide.

18. A photographic element comprising a baryta coated paper bearing a light-sensitive, water-permeable organic protective colloid-silver halide emulsion which has uniformly dispersed therethrough finely divided particles of a polytetrafiuoroethylene, said particles having sizes within the range from 0.05 to 25.0 microns and being present in an amount of 50 to 500 grams per 1.5 mols of silver halide.

References Cited in the file of this patent UNITED STATES PATENTS i l i 

1. A PROCESS OF DELUSTERING WATER-PERMEABLE, ORGANIC, PROTECTIVE COLLOID LAYERS WHICH COMPRISES ADMIXING AN AQUEOUS SOLUTION OF WATER-PERMEABLE, ORGANIC, PROTECTIVE COLLOID WITH AN AQUEOUS DISPERSION OF FINELY DIVIDED PARTICLES OF AN ETHYLENIC ADDITION POLYMER AT LEAST 65% BY WEIGHT OF A POLYMER UNITS BEING FLUORINE-SUBSTITUTED ETHYLENE UNITS CONTAINING 3 TO 4 FLUORINE ATOMS, SAID PARTICLES HAVING SIZES WITHIN THE RANGE OF 0.05 TO 25.0 MICRONS, AND COATING THE RESULTING DISPERSION ONTO A SHEET SUPPORT. 